Method and System for Transporting and Storing At Least Two Wind Turbine Blades

ABSTRACT

A transportation and storage system for at least two wind turbine blades and comprising a first wind turbine blade and a second wind turbine blade is described. The wind turbine blades each having a root end and a tip end, said system comprising a packaging system that is adapted to placing the first wind turbine blade so that the tip end of the first wind turbine blade points in a first direction, and placing the second wind turbine blade so that the tip end of the second wind turbine blade points in a second direction, which is substantially opposite to the first direction. The tip end of the second wind turbine blade extends beyond the root end of the first wind turbine blade, and the tip end of the first wind turbine blade extends beyond the root end of the second wind turbine blade, when the first and the second wind turbine blades are arranged in the packaging system.

FIELD OF THE INVENTION

The present invention relates to a method of transporting or storing ofwind turbine blades as well as a transportation and storing system fortransporting at least two wind turbine blades including a first windturbine blade and a second wind turbine blade.

BACKGROUND OF THE INVENTION

Wind turbine blades used for horizontal axis wind turbines forgenerating electrical power from the wind can be rather large and maytoday exceed 70 metres in length and 4 metres in width. The blades aretypically made from a fibre-reinforced polymer material and comprisingan upwind shell part and a downwind shell part. Due to the size andfragility of these large rotor blades, the blades may be damaged duringtransport as well as during loading and unloading. Such damages mayseriously degrade the performance of the blades. Therefore, the bladesneed to be carefully packaged in order to ensure that they are notdamaged.

However, due to the increasing length of modern wind turbine blades, itis gradually becoming more complicated and expensive to transport theblades. It is not uncommon that the transportation costs amount to 20percent of the total costs for manufacturing, transporting and mountingthe wind turbine blade on the rotor of a wind turbine blade. Also, someblades are transported to the erection site through different modes oftransport, such as by truck, train and ship. Some of these modes oftransports may have restrictions on large loads, maximum heights,maximum widths, maximum distances between transport frames or supports,for instance dictated by local regulations. Therefore, there exists alogistic problem of providing transport solutions that are suitable forvarious types of transport.

Overall, there is a demand for making transport solutions simpler, saferand cheaper. The prior art shows various solutions for transporting morethan one rotor blade using a single container or other packaging system,which is an obvious way to reduce the transport costs. However, theafore-mentioned restrictions and limits may increase the difficulty oftransporting a plurality of blades using the same packaging system.EP1387802 discloses a method and system for transporting two straightwind turbine blades, where the root end of a first blade is arranged ina first package frame, and the tip end of a second, neighbouring bladeis arranged in a second package frame that is arranged next to andconnected to the first package frame with the effect that the blades arestored compactly alongside each other in a “tip-to-root” arrangement.However, in this transport system the tip end frames support the bladesat the very tip of the blades, where they are mechanically most fragile.Further, the package frames are arranged at the root end face and theblade tip. Therefore, the distance between the package frames areapproximately equal to the length of the blades. For very long blades of45 metres or longer, this might not be possible due to local regulationsand restrictions on transport.

US 2011/0142660 discloses a wind turbine blade, which is provided withan integrated attachment bore through the spar caps of the blades. Theattachment bores are structurally configured for receipt of a handlingmechanism for supporting the blade during transport. Two blades may bearranged in a tip-to-root configuration, where the tip end of one bladeis arranged nearly adjacent the root end of a second blade.

WO 2011/098086 discloses a system for transporting a wind turbinecomponent via a first railcar and a second railcar. One embodiment showsthe transport of two blades in a tip-to-root configuration, where afirst frame is mounted on a first support member slidingly androtatingly coupled to the first railcar, and a second frame is mountedon a second support member rotatingly coupled to a second rail car. Thetip end of one blade is arranged nearly adjacent the root end of asecond blade.

It is therefore an object of the invention to obtain a new method andsystem for storing and transporting a plurality of wind turbine blades,which overcome or ameliorate at least one of the disadvantages of theprior art or which provide a useful alternative.

SUMMARY OF THE INVENTION

According to a first aspect, this is obtained by a method fortransporting or storing at least two wind turbine blades and comprisinga first wind turbine blade and a second wind turbine blade, the windturbine blades each having a root end and a tip end, wherein the methodcomprises the steps of: a) attaching a first root end frame in form of afirst root end bracket to a root end face of the first wind turbineblade, b) arranging the tip end of the first wind turbine in a first tipend frame, c) attaching a second root end frame in form of a second rootend bracket to a root end face of the second wind turbine blade, d)arranging the tip end of the second wind turbine in a second tip endframe, e) placing the first wind turbine blade so that the tip end ofthe first wind turbine blade points in a first direction, f) placing thesecond wind turbine blade adjacent and in immediate vicinity to thefirst wind turbine blade so that the tip end of the second wind turbineblade points in a second direction, which is substantially opposite tothe first direction, and, if not already connected, g) connecting thesecond tip end frame to the first root end frame, and connecting thefirst tip end frame to the second root end frame so that the tip end ofthe second wind turbine blade extends beyond the root end of the firstwind turbine blade. The tip end of the first wind turbine blade may alsoextend beyond the root end of the second wind turbine blade. This willinevitably be the case, if the first wind turbine blade and the secondwind turbine blade are of the same length. It is also clear that the tipend of the first wind turbine blade extends beyond the second rootframe, and that the tip end of the second wind turbine blade extendsbeyond the first root frame.

Thus, it is clear that the two wind turbine blades are arrangedsubstantially parallel to each other and oriented in oppositedirections. Since the thickness of the blades is typically decreasingfrom the root end towards the tip end, the blades can with the new“tip-to-root” layout be arranged on top of each other via frames havinga relatively small combined cross-section. Further, the new setupensures that a tip end section of the second wind turbine blade may besupported farther from the tip end than with a common frame assembly forsupporting the root of the first wind turbine blade and a tip section ofthe second blade. Thereby, the tip end section may be supported at aposition where the blade is mechanically stronger than right at the tipend. The first root end bracket and the second root end bracket providea particularly simple solution, where the frame or bracket may beattached to for instance a root end plate of the blade and withouthaving to support the exterior of the blade. Thus, external damages tothe outer surface of the blades may more easily be avoided. The tip endframes (e.g. with receptacles) may be attached to the brackets, so thatthe tip end extends beyond the bracket, when the blade is inserted intothe tip end frame (and receptacle).

Additionally, the new transport layout ensures that the frame assembliesmay be arranged longitudinally closer to each other, thereby being ableto abide to local regulations that may put restrictions on the maximumdistance between support frames for transport.

According to an advantageous embodiment, the first wind turbine bladeand the second wind turbine blade in steps e) and f) are stacked on topof each other, i.e. so that the second wind turbine blade is arrangedabove the first wind turbine blade. Advantageously, the first windturbine blade and the second wind turbine blade are arranged so thatchordal planes of their respective tip ends are arranged substantiallyhorizontally. By “substantially horizontally” is meant that the chordalplane may vary up to +/−25 degrees to horizontal, in particular sincethe chordal plane may be twisted along the span of the wind turbineblade.

In a preferred embodiment, the blades are arranged so that an upwindside (or pressure side) of the blade is facing substantially downwards.

According to an alternative embodiment, the first wind turbine blade andthe second wind turbine blade in steps e) and f) are stackedside-by-side. In such an embodiment, the first wind turbine blade andthe second wind turbine blade may advantageously be arranged so thatchordal planes of their respective tip ends are arranged substantiallyvertically. Thus, the blades may for instance be arranged so that theyare supported at their leading edges (which are mechanically strongerthan the trailing edges) via an upwardly facing receptacle.

In a stacking system for storing more than two blades, it is alsopossible to stack the blades both horizontally and vertically, i.e. in astacked array.

The method advantageously relates to transport and storage of bladeshaving a blade length of at least 40 metres, or at least 45 metres, oreven at least 50 metres. The blades may be prebent so that, when mountedon an upwind configured horizontal wind turbine in a non-loaded state,they will curve forward out of the rotor plane so that the tip to towerclearance is increased.

The first and the second wind turbine blades may be prebent. Suchprebent blades may be arranged in the tip end frames and root end framesso that they are straightened slightly or fully during transport, e.g.as shown in WO05005286 by the present applicant. However, the bladesneed not forcedly be straightened. Since the blades are supported nearthe ends and the blades are arranged with the upwind side facingdownwards, the own weight of the blade may straighten the blades due tothe gravitational forces acting on the middle part of the blade.

The tip end frames preferably comprise a receptacle for supporting a tipend section. Thus, the first tip end frame comprises a first tip endreceptacle, and the second tip end frame comprises a second tip endreceptacle. Depending on the particular solution, the receptacle may forinstance either support the pressure side of the blade or alternativelythe leading edge of the blade. However, in principle the receptacle mayalso support the suction side of the blade or even the trailing edge ofthe blade. The frames themselves may be used as lifting tools so thattwo or more blades may be lifted in one go and without imposing stressto the blades.

In a particularly advantageous embodiment, the second tip end frame isdetachably connected to the first root end frame, and the first tip endframe is detachably connected to the second root end frame. Thus, it isclear that the frames may be constructed as an integral solutioncomprising both a root end frame and a tip end frame (or receptacle), oras separate frames for the root and the tip. The latter solution has theadvantage, that the second blade may more easily be disengaged from thefirst blade, simply by detaching the tip end frames from the root endframes.

In another embodiment, the connection parts of the root end frames andthe tip end frames that connect to or fix the blade in the frame may behinged to the frame itself. This can for instance for the root beachieved by connecting a plate to the root of the blade that is hingedlyconnected to the frame. Similarly, this can be achieved by letting a tipend receptacle be hingedly connected to the tip end frame. Suchembodiments have the advantage of alleviating loads that would otherwisebe introduced to either the frames or blades due to blade deflections orthe like during transport.

In yet another advantageous embodiment, the first root end frame and thesecond tip end frame are connected in a L-shaped or T-shapedconfiguration so that a base of the L- or T-shaped configuration isattached to the root end of the first wind turbine blade, and atransversely extending frame part (or extremity) of the L- or T-shapedconfiguration supports a longitudinal section of the tip end of thesecond wind turbine blade. The same of course also applies to the secondroot end frame and the first tip end frame. Advantageously, the L- orT-shaped configuration is formed so that the base is a root end facebracket attached to the root end face of the first blade, and thetransversely extending frame part supports a tip end section of thesecond blade.

The frame connection is arranged so that the base of the L- orT-configuration is arranged vertically. The transversely extending framepart may be arranged to that it extends from the top or the bottom ofthe base. In this configuration the second wind turbine blade isarranged on top of the first wind turbine blade. The extremity ortransversely extending frame part may thus support either a part of thesuction side or the pressure side of the blade in an upwardly facingreceptacle. Alternatively, the extremity may extend from the side of thebase. In such a configuration, the blades are arranged side-by-side, andthe extremity or transversely extending frame part may support either apart of the leading edge or the trailing edge of the blade in anupwardly facing receptacle.

If the blades are arranged so that both blades are facing with theleading edge downwards (in the side-by-side arrangement) or with theupwind shell parts facing downwards (in the vertically stackedarrangement), it is clear that the transversely extending frame parts ofthe two frame assemblies must be arranged inversely compared to the baseframe. Thus, the two frame assemblies have slightly differentconfigurations.

The L- or T-shaped frame assembly has the advantage that thetransversely extending frame supports a larger part of the tip sections,thus better alleviating loads and possibly also minimising the necessaryoverhang of the tip part that extends beyond the root end frame.

In one embodiment, the longitudinal extent of the transversely extendingframe part is at least 1 meter, advantageously at least 1.5 metres, moreadvantageously at least 2 metres. The longitudinal section of the tipend of the blade may be supported along the entire section, or it may besupported in a plurality of discrete sections within the extremity ofthe L- or T-shaped frame assembly.

As an alternative to the L- or T-shaped frame assembly, the root endframe and the tip end frame may be arranged substantially in the sameplane.

Advantageously, a plurality of first wind turbine blades and second windturbine blades are placed in an array, and wherein the wind turbineblades each comprise a shoulder defining a maximum chord of the blade,and wherein the blades are arranged so that the maximum chord forms anangle of between 20 and 75 degrees to a horizontal plane, advantageouslybetween 22 and 73 degrees. Even more advantageously, the maximum chordforms an angle of between 15 and 35 degrees to a horizontal plane,advantageously between 20 and 30 degrees. It is clear that this stackingmethod may be advantageous to any configuration of stacking blades sideby side with the root end and tip end arranged in the same direction. Ina preferred embodiment, it is the root end of the blade that is turnedbetween 15 and 35 degrees to a horizontal plane, advantageously between20 and 30 degrees. The angle may for instance be defined by bond linesbetween an upwind shell part and a downwind shell part at the root endof the blade. In this setup, the blades in a stacked array may bearranged so that they slightly overlap with the shoulder of one bladeextending partly over an adjacent blade, so that the upwind side of oneblade near the shoulder faces down towards the downwind side near theleading edge of an adjacent blade. Thereby, it is possible to stack theblades in frames having a width corresponding to the diameter of theroot or only slightly larger, even though the chord length of theshoulder exceeds this diameter.

In another embodiment, intermediate protection members are arrangedbetween the first wind turbine blade and the second wind turbine blade.The intermediate protection members are preferably arranged at alongitudinal position between the first root end frame and the secondroot end frame. Advantageously, the intermediate protection members arearranged near the tip end frames so as to provide additional support toa tip end section of the wind turbine blade. The protection meansprevent the blades from being damaged due to bending or the bladesimpacting each other. The intermediate protection members areparticularly advantageous, when the blades are stacked on top of eachother. In such a setup, the intermediate protection members may be usedas support for supporting an additional tip end section of one blade andmay transfer loads from the tip end of the upper blade to themechanically stronger root region of the lower blade. Additionalprotection members may be arranged below the lowermost blade in astacked array and a support platform or the ground. The additionalprotection member is advantageously arranged to support an additionaltip end section of the lowermost blade, e.g. near the tip end frame ofthe lowermost blade.

The intermediate protection members may be made of a foamed polymer.

In another embodiment, a root end face of the first wind turbine bladeis arranged within 45 metres of a root end face of the second windturbine blade, advantageously within 42 metres. Accordingly, root endbrackets or frames should also be arranged at maximum 45 metres or 42metres from each other.

According to the first aspect, the invention also provides atransportation and storage system for at least two wind turbine bladesand comprising a first wind turbine blade and a second wind turbineblade. The wind turbine blades each have a root end and a tip end. Thesystem comprises a packaging system that is adapted to placing the firstwind turbine blade so that the tip end of the first wind turbine bladepoints in a first direction, and placing the second wind turbine bladeso that the tip end of the second wind turbine blade points in a seconddirection, which is substantially opposite to the first direction. Thepackaging system comprises a first root end frame in form of a firstroot end bracket for attachment to a root end face of the first windturbine blade, a first tip end frame for supporting a tip end portion ofthe first wind turbine blade, a second root end frame in form of asecond root end bracket for attachment to a root end face of the secondwind turbine blade, and a second tip end frame for supporting a tip endportion of the second wind turbine blade. The second tip end frame isconnected to the first root end frame, and the first tip end frame isconnected to the second root end frame so that the tip end of the secondwind turbine blade extends beyond the root end of the first wind turbineblade, and the tip end of the first wind turbine blade extends beyondthe root end of the second wind turbine blade, when the first and thesecond wind turbine blades are arranged in the packaging system. It isalso clear that the tip end of the first wind turbine blade extendsbeyond the second root frame, and that the tip end of the second windturbine blade extends beyond the first root frame. Thus, again it isclear that the system is adapted to arranging the first and the secondwind turbine blades substantially parallel to each other and pointingtip to root but with an overhang. The first root end bracket and secondroot end bracket provide a particularly simple solution, where the frameor bracket may be attached to for instance a root end plate of the bladeand without having to support the exterior of the blade. Thus, externaldamages to the outer surface may more easily be avoided. The tip endframes (with receptacles) may be attached to the brackets, so that thetip end extends beyond the bracket, when the blade is inserted into thetip end frame (and receptacle).

The second tip end frame may be detachably connected to the first rootend frame, and the first tip end frame may be detachably connected tothe second root end frame. Thus, it is clear that the frames may beconstructed as an integral solution comprising both a root end frame anda tip end frame (or receptacle), or as separate frames for the root andthe tip. The latter solution has the advantage, that the second blademay more easily be disengaged from the first blade, simply by detachingthe tip end frames from the root end frames.

In the tip end of the first wind turbine blade, when arranged in thefirst tip end frame, extends a first longitudinal extent beyond thefirst tip end frame, and the tip end of the second wind turbine blade,when arranged in the second tip end frame, extends a second longitudinalextent beyond the first tip end frame. In other words, the first tip endframe is adapted to package the tip end of first wind blade at a firstdistance from the tip, and the second tip end frame is adapted topackage the tip end of the tip end of the second wind turbine blade at afirst distance from the tip. The first distance and the second distancewill of course typically be approximately the same. The firstlongitudinal extent and the second longitudinal extent may be at least 2metres, advantageously at least 3.5 metres, and more advantageously, atleast 5 metres. The blade tip may even extend at least 6, 7, or 8 metresbeyond the tip end frame (and accordingly also the root end frame). Thefirst longitudinal extent and second longitudinal extent may be at least2.5%, or at least 5%, or at least 7.5%, or at least 10% of the bladelengths of the first wind turbine blade and second wind turbine blade,respectively.

In a particular advantageous embodiment, the storage system is adaptedto stack the first and the second wind turbine blade on top of eachother. The second tip end frame may for instance be attached to a top ofthe first root end frame, and the first tip end frame is attached to abottom of the second root end frame. In this setup the blades arearranged so that chord planes of the tip ends of the blades are arrangedsubstantially horizontally. The setup may be adapted to arrange theblades with an upwind shell part substantially downwards.

In an alternative embodiment, the tip end frames are attached to sidesof the root end frames. In such a setup the chord planes of tip end ofthe blades are arranged substantially vertically, advantageously with aleading edge facing downwards.

In another embodiment, at least a first intermediate protective memberis arranged between the first wind turbine blade and the second windturbine blade. The first intermediate protective member mayadvantageously be arranged near the tip end of an upper arranged bladeof the first wind turbine blade and the second wind turbine blade.Additionally, a second protective member may be arranged below the lowerof the two wind turbine blades. In a stacked array, this blade will thenalso be an intermediate protective member arranged between two blades.Further, a protective member may be arranged below the lowermost bladein the stacked array. The intermediate protective members may be made ofa foamed polymer.

It is clear that some of the provided solution may also be used forother configurations of transporting and storing blades, e.g. withoutthe tip overhang.

Thus, according to a second aspect, the invention provides a method fortransporting or storing at least two wind turbine blades and comprisinga first wind turbine blade and a second wind turbine blade, the windturbine blades each having a root end and a tip end, wherein the methodcomprises the steps of:

-   a) placing the root end of the first wind turbine blade in a first    root end frame,-   b) placing a tip end section of the first wind turbine blade in a    first tip end frame,-   c) placing the root end of the second wind turbine blade in a second    root end frame, so that the second root end frame is arranged near    the first tip end frame with the first tip end frame substantially    above the second root end frame,-   d) placing a tip end section of the second wind turbine blade in a    second tip end frame, so that the second tip end frame is arranged    near the first root end frame with the second tip end frame    substantially below the first root end frame, wherein the method    comprises the additional step of arranging an intermediate    protection means between the first wind turbine blade and the second    wind turbine blade.

According to the second aspect, the invention also provides atransportation and storage system for at least two wind turbine bladesand comprising a first wind turbine blade and a second wind turbineblade, the wind turbine blades each having a root end and a tip end,said system comprising a packaging system that is adapted to placing thefirst wind turbine blade so that the tip end of the first wind turbineblade points in a first direction, and placing the second wind turbineblade so that the tip end of the second wind turbine blade points in asecond direction, which is substantially opposite to the firstdirection, wherein the transportation and storage system includes apackaging system that comprises:

-   -   a first root end frame for attachment to the root end of the        first wind turbine blade, a first tip end frame for supporting a        tip end portion of the first wind turbine blade,    -   a second root end frame for attachment to the root end of the        second wind turbine blade, and    -   a second tip end frame for supporting a tip end portion of the        second wind turbine blade, wherein the packaging system further        comprises an intermediate protection means arranged between the        first wind turbine blade and the second wind turbine blade.

According to a third aspect, the invention provides a method fortransporting or storing at least two wind turbine blades and comprisinga first wind turbine blade and a second wind turbine blade, the windturbine blades each having a root end and a tip end, wherein the methodcomprises the steps of:

-   a) placing the root end of the first wind turbine blade in a first    root end frame,-   b) placing a tip end section of the first wind turbine blade in a    first tip end frame,-   c) placing the root end of the second wind turbine blade in a second    root end frame,-   d) placing a tip end section of the second wind turbine blade in a    second tip end frame, wherein    -   the first root end frame and the second tip end frame as well as        the first tip end frame and the second root end frame are        connected as L-shaped or T-shaped frame assemblies so that bases        of the frame assemblies are attached to the root ends of the        first and the second wind turbine blade, and extremities of the        frame assemblies support a longitudinal section of the tip ends        of the first and the second wind turbine blades.

According to the third aspect, the invention also provides atransportation and storage system for at least two wind turbine bladesand comprising a first wind turbine blade and a second wind turbineblade, the wind turbine blades each having a root end and a tip end,said system comprising a packaging system that is adapted to placing thefirst wind turbine blade so that the tip end of the first wind turbineblade points in a first direction, and placing the second wind turbineblade so that the tip end of the second wind turbine blade points in asecond direction, which is substantially opposite to the firstdirection, wherein the transportation and storage system includes apackaging system that comprises:

-   -   a first root end frame for attachment to the root end of the        first wind turbine blade,    -   a first tip end frame for supporting a tip end portion of the        first wind turbine blade,    -   a second root end frame for attachment to the root end of the        second wind turbine blade, and    -   a second tip end frame for supporting a tip end portion of the        second wind turbine blade, wherein    -   the first root end frame and the second tip end frame as well as        the first tip end frame and the second root end frame are        connected as L-shaped or T-shaped frame assemblies so that bases        of the frame assemblies are attached to the root ends of the        first and the second wind turbine blades, and extremities of the        frame assemblies support a longitudinal section of the tip ends        of the first and the second wind turbine blades.

Further, according to the third aspect, the invention provides a frameassembly for use in transport and storing of wind turbine blades,wherein the frame assembly comprises a root end frame part forattachment to a root end of a first wind turbine blade and a tip endframe part for supporting a tip end section of a second blade, whereinthe root end frame part and the tip end frame part are attached in anL-shaped or T-shaped configuration.

According to a fourth aspect, the invention provides a transportationand storage system for at least two wind turbine blades and comprising afirst wind turbine blade and a second wind turbine blade, the windturbine blades each having a root end and a tip end as well as ashoulder defining a maximum chord of the blade, wherein the methodcomprises the steps of:

-   a) placing the root end of the first wind turbine blade in a first    root end frame,-   b) placing a tip end section of the first wind turbine blade in a    first tip end frame,-   c) placing the root end of the second wind turbine blade in a second    root end frame,-   d) placing the tip end section of the second wind turbine blade in a    second tip end frame,-   e) arranging the first and the second blade parallel to each other    so that the first root end frame is placed adjacent the second root    end frame, and the first tip end frame is arranged adjacent the    second tip end frame, wherein

the first wind turbine blade and the second wind turbine blade arearranged so that the maximum chord of the blades form angles of between15 and 35 degrees to a horizontal plane, advantageously between 20 and30 degrees, more advantageously around 25 degrees.

The advantages of the method and system according to the second, thirdand fourth aspects have previously been explained. It is clear that allthe embodiments described with respect to the first aspect of theinvention also apply to the second, third, and fourth aspect of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is explained in detail below with reference to anembodiment shown in the drawings, in which

FIG. 1 shows a wind turbine,

FIG. 2 shows a schematic view of a wind turbine blade according to theinvention,

FIG. 3 shows a schematic view of an airfoil profile,

FIG. 4 shows a schematic view of the wind turbine blade according to theinvention, seen from above and from the side,

FIG. 5 shows a schematic side view of a first wind turbine blade and asecond wind turbine blade stored in a packaging system according to theinvention,

FIG. 6 illustrates how the blades are oriented in the packaging systemaccording to the invention,

FIG. 7 shows a schematic end view of blades stored in a stacked array ofpackaging systems according to the invention,

FIG. 8 shows a top view of the mutual arrangement of blades when stackedin an array,

FIG. 9 shows a schematic side view of a number of first wind turbineblades and second wind turbine blades stored in a packaging systemaccording to the invention with intermediate protection means arrangedbetween the blades, and

FIG. 10 shows a perspective view of blades stored in a stacked array ofpackaging systems in an alternative embodiment of the invention.

The present invention relates to transport and storage of wind turbineblades for horizontal axis wind turbines (HAWTs).

FIG. 1 illustrates a conventional modern upwind wind turbine accordingto the so-called “Danish concept” with a tower 4, a nacelle 6 and arotor with a substantially horizontal rotor shaft. The rotor includes ahub 8 and three blades 10 extending radially from the hub 8, each havinga blade root 16 nearest the hub and a blade tip 14 furthest from the hub8. The rotor has a radius denoted R.

FIG. 2 shows a schematic view of a first embodiment of a wind turbineblade 10. The wind turbine blade 10 has the shape of a conventional windturbine blade and comprises a root region 30 closest to the hub, aprofiled or an airfoil region 34 furthest away from the hub and atransition region 32 between the root region 30 and the airfoil region34. The blade 10 comprises a leading edge 18 facing the direction ofrotation of the blade 10, when the blade is mounted on the hub, and atrailing edge 20 facing the opposite direction of the leading edge 18.

The airfoil region 34 (also called the profiled region) has an ideal oralmost ideal blade shape with respect to generating lift, whereas theroot region 30 due to structural considerations has a substantiallycircular or elliptical cross-section, which for instance makes it easierand safer to mount the blade 10 to the hub. The diameter (or the chord)of the root region 30 may be constant along the entire root area 30. Thetransition region 32 has a transitional profile gradually changing fromthe circular or elliptical shape of the root region 30 to the airfoilprofile of the airfoil region 34. The chord length of the transitionregion 32 typically increases with increasing distance r from the hub.The airfoil region 34 has an airfoil profile with a chord extendingbetween the leading edge 18 and the trailing edge 20 of the blade 10.The width of the chord decreases with increasing distance r from thehub.

A shoulder 40 of the blade 10 is defined as the position, where theblade 10 has its largest chord length. The shoulder 40 is typicallyprovided at the boundary between the transition region 32 and theairfoil region 34.

It should be noted that the chords of different sections of the bladenormally do not lie in a common plane, since the blade may be twistedand/or curved (i.e. pre-bent), thus providing the chord plane with acorrespondingly twisted and/or curved course, this being most often thecase in order to compensate for the local velocity of the blade beingdependent on the radius from the hub.

The wind turbine blade 10 comprises a shell made of fibre-reinforcedpolymer and is typically made as a pressure side or upwind shell part 24and a suction side or downwind shell part 26 that are glued togetheralong bond lines 28 extending along the trailing edge 20 and the leadingedge 18 of the blade 10.

FIGS. 3 and 4 depict parameters, which are used to explain the geometryof the wind turbine blades to be stored and transported according to theinvention.

FIG. 3 shows a schematic view of an airfoil profile 50 of a typicalblade of a wind turbine depicted with the various parameters, which aretypically used to define the geometrical shape of an airfoil. Theairfoil profile 50 has a pressure side 52 and a suction side 54, whichduring use—i.e. during rotation of the rotor—normally face towards thewindward (or upwind) side and the leeward (or downwind) side,respectively. The airfoil 50 has a chord 60 with a chord length cextending between a leading edge 56 and a trailing edge 58 of the blade.The airfoil 50 has a thickness t, which is defined as the distancebetween the pressure side 52 and the suction side 54. The thickness t ofthe airfoil varies along the chord 60. The deviation from a symmetricalprofile is given by a camber line 62, which is a median line through theairfoil profile 50. The median line can be found by drawing inscribedcircles from the leading edge 56 to the trailing edge 58. The medianline follows the centres of these inscribed circles and the deviation ordistance from the chord 60 is called the camber f. The asymmetry canalso be defined by use of parameters called the upper camber (or suctionside camber) and lower camber (or pressure side camber), which aredefined as the distances from the chord 60 and the suction side 54 andpressure side 52, respectively.

Airfoil profiles are often characterised by the following parameters:the chord length c, the maximum camber f, the position d_(f) of themaximum camber f, the maximum airfoil thickness t, which is the largestdiameter of the inscribed circles along the median camber line 62, theposition d_(t) of the maximum thickness t, and a nose radius (notshown). These parameters are typically defined as ratios to the chordlength c. Thus, a local relative blade thickness t/c is given as theratio between the local maximum thickness t and the local chord lengthc. Further, the position d_(p) of the maximum pressure side camber maybe used as a design parameter, and of course also the position of themaximum suction side camber.

FIG. 4 shows other geometric parameters of the blade. The blade has atotal blade length L. As shown in FIG. 3, the root end is located atposition r=0, and the tip end located at r=L. The shoulder 40 of theblade is located at a position r=L_(w), and has a shoulder width W,which equals the chord length at the shoulder 40. The diameter of theroot is defined as D. Further, the blade is provided with a prebend,which is defined as Δy, which corresponds to the out of plane deflectionfrom a pitch axis 22 of the blade.

Blades have over the time become longer and longer and may now exceed alength of 70 metres. The length of the blades as well as the shape ofthe blades with respect to shoulder, twist and prebending makes itincreasingly difficult to transport the blades, in particular if aplurality of blades is to be transported and stored together. The shapeand size of the blades also puts limitations on how closely the bladescan be stored in a stacked array.

FIG. 5 shows a schematic view of first embodiment of a transportationand storage system according to the invention for transporting andstoring a first wind turbine blade and a second wind turbine blade 10.The transportation and storage system includes a packaging system thatcomprises a first frame assembly 70. The first frame assembly 70 iscomposed of a root end frame 71 in form of a root end bracket forattachment to a root end face 17 of the first wind turbine blade, and atip end frame 72 for supporting a tip end section 15 of the second windturbine blade. The first frame assembly has an L-shaped configuration,where the root end bracket 71 forms the base of the L-shaped assembly,and the tip end frame 72 forms a transversely extending frame part (orextremity) that extends from the top of root end bracket 71. The secondframe assembly 80 is also composed of a root end frame 81 in form of aroot end bracket for attachment to a root end face 17 of the second windturbine blade, and a tip end frame 82 for supporting a tip end section15 of the first wind turbine blade. The first frame assembly has anL-shaped configuration, where the root end bracket 81 forms the base ofthe L-shaped assembly, and the tip end frame 82 forms a transverselyextending frame part (or extremity) that extends from the bottom of rootend bracket 81.

In terms of the following claims, it is clear that the first frameassembly comprises the first root end frame and the second tip endframe, whereas the second frame assembly comprises the second root endframe and the first tip end frame.

Some local regulations have limitations on the maximum distance l_(f)between supports for transporting items, for instance a maximum of 42metres. The packaging system accommodates for such regulations by beingdesigned so that the tip ends of the first wind turbine blade and thesecond wind turbine blade extend beyond the root end frames 70, 80 sothat a longitudinal extent l_(o) or overhang of the tip ends extendsbeyond the root end frames 70, 80, thereby being able to transportblades of lengths exceeding the maximum distance l_(f) between supports.Further, this novel setup has the advantage that the tip end sectionsare supported at a distance from the respective tip ends, where theblades are mechanically stronger than right at the tip. Thus, theprobability of the frames damaging the blades is lowered significantly.Further, the L-shaped configuration of the frame assemblies 70, 80 isadapted to support the tip ends over a longitudinal extent of e.g. atleast 1 metre, thereby ensuring an even better support for the blades.

The tip end frames 72, 82 may advantageously comprise one or morereceptacles having an upwardly facing support face for supporting a partof the upwind side of the blade. Further, the tip end frames 72, 82 mayadvantageously be detachably coupled to the root end frames 71, 81.

In the shown setup, the blades are arranged with the pressure side (orupwind side) facing substantially downwards. Thereby, the blades arealso arranged so that the middle part of the blade is spaced furtherfrom the support surface or ground due to the prebending of the blades.However, the blades are as shown in FIG. 6 turned so that the bond lines28 as well as the chord of the shoulder 40 forms an angle α ofapproximately 25 degrees to a horizontal line 29. This has a furtheradvantage, when blades are stacked in arrays comprising first and secondframe assemblies 70, 80 and accordingly comprising an array of storedfirst and second wind turbine blades, since the blades may be stackedmore compactly than conventional systems for transporting and storingsuch blades. This is better illustrated in FIGS. 7 and 8 that showblades stacked in an array, where FIG. 7 shows an end view of thetransportation and storage system with the blades stored in the system,and FIG. 8 shows a top view of the blades in the array with the storagesystem removed from the figure in order to better illustrate the mutualarrangement of the blades.

From the end view shown in FIG. 7, it is seen that the first blades thathave their root end faces attached to the root end brackets 71 arearranged so that the shoulders of the blades 40 point slightly upwardsand to the right, whereas the second blades that have their tip endsections supported in the tip end frames 72 are arranged so that theshoulders 40 point upwards and towards the left side of the figure.Thereby, the blades can be stacked side by side in frames that are onlyslightly wider than the root diameter D of the blades.

In the top view shown in FIG. 8, it is seen that the blades are arrangedso that they slightly overlap with the shoulder 40 of one bladeextending partly over an adjacent blade, so that the upwind side of oneblade near the shoulder faces down towards the downwind side near theleading edge of an adjacent blade.

In some situations it may be advantageous to provide additional supportmembers for taking up loads from the blades, for instance by providingintermediate support members 90 between the first and the second windturbine blades as shown in FIG. 9.

The intermediate support members 90 may advantageously be arranged nearthe tip end of the upper blade so that loads may be transferred from atip section of the upper blade to a root section of a lower blade. Anadditional protection member 92 may be arranged between the lowermostblade in an array and the support platform or ground. The protectionmembers 90, 92 may for instance be made of a foamed polymer.

The invention has been described with reference to a preferredembodiment. However, the scope of the invention is not limited to theillustrated embodiment, and alterations and modifications can be carriedout without deviating from the scope of the invention that is defined bythe following claims. The packaging system has for instance beendescribed in relation to an L-shaped frame assembly. However, in anotheradvantageous embodiment, the frame assembly may be T-shaped so that theroot end bracket is attached to the tip end frame at an intermediatepart thereof. Also, the blades may be stacked in a packaging system,where the root end frames and tip end frames are arranged in the sameplane as shown in FIG. 10. The transportation and storage system hasalso been described in a configuration, where the second wind turbineblade is arranged above the first wind turbine blade. However, it isclear that the system could also be arranged in a configuration, wherethe first and the second wind turbine blades are arranged side-by-side.In such a configuration, the blades would instead be arranged so thatthe bond lines and chord of the shoulder form an angle of approximately25 degrees compared to vertical. Further, the receptacles of the tip endframes could instead be adapted to support the leading edge of a tip endsection instead.

LIST OF REFERENCE NUMERALS

-   2 wind turbine-   4 tower-   6 nacelle-   8 hub-   10 blade-   14 blade tip-   15 tip end section-   16 blade root-   17 root end face-   18 leading edge-   20 trailing edge-   22 pitch axis-   24 pressure side shell part/upwind shell part-   26 suction side shell part/downwind shell part-   28 bond lines-   29 horizontal-   30 root region-   32 transition region-   34 airfoil region-   50 airfoil profile-   52 pressure side/upwind side-   54 suction side/downwind side-   56 leading edge-   58 trailing edge-   60 chord-   62 camber line/median line-   70 first frame assembly-   71 root end frame/root end bracket (of first frame assembly)-   72 tip end frame/transversely extending frame part (of first frame    assembly)-   80 first frame assembly-   81 root end frame/root end bracket (of first frame assembly)-   82 tip end frame/transversely extending frame part (of first frame    assembly)-   90 intermediate protection member-   92 additional protection member-   c chord length-   d_(t) position of maximum thickness-   d_(f) position of maximum camber-   d_(p) position of maximum pressure side camber-   f camber-   l_(f) longitudinal distance between root end frames-   l_(o) longitudinal extent of blade tip overhang-   L blade length-   r local radius, radial distance from blade root-   t thickness-   Δy prebend

1-13. (canceled)
 14. A transportation and storage system for at leasttwo wind turbine blades and comprising a first wind turbine blade and asecond wind turbine blade, the wind turbine blades each having a rootend and a tip end, said system comprising a packaging system that isadapted to placing the first wind turbine blade so that the tip end ofthe first wind turbine blade points in a first direction, and placingthe second wind turbine blade so that the tip end of the second windturbine blade points in a second direction, which is substantiallyopposite to the first direction, and wherein the packing systemcomprises: a first root end frame in form of a first root end bracketfor attachment to a root end face of the first wind turbine blade, afirst tip end frame for supporting a tip end portion of the first windturbine blade, a second root end frame in form of a second root endbracket for attachment to a root end face of the second wind turbineblade, and a second tip end frame for supporting a tip end portion ofthe second wind turbine blade, wherein the second tip end frame isconnected to the first root end frame, and the first tip end frame isconnected to the second root end frame so that the the tip end of thesecond wind turbine blade extends beyond the root end of the first windturbine blade, and the tip end of the first wind turbine blade extendsbeyond the root end of the second wind turbine blade, when the first andthe second wind turbine blades are arranged in the packaging system. 15.The transportation and storage system according to claim 14, wherein thesecond tip end frame is detachably connected to the first root endframe, and the first tip end frame is detachably connected to the secondroot end frame.
 16. The transportation and storage system according toclaim 14, wherein the tip end of the first wind turbine blade, whenarranged in the first tip end frame, extends a first longitudinal lengthbeyond the first tip end frame, and the tip end of the second windturbine blade, when arranged in the second tip end frame, extends asecond longitudinal length beyond the first tip end frame
 17. Thetransportation and storage system according to claim 16, wherein thefirst longitudinal extent and the second longitudinal extent are atleast 2 metres.
 18. The transportation and storage system according toclaim 14, wherein the storage system is adapted to stack the first andthe second wind turbine blades on top of each other.
 19. Thetransportation and storage system according to claim 14, wherein thesecond tip end frame is attached to a top of the first root end frame,and the first tip end frame is attached to a bottom of the second rootend frame.
 20. The transportation and storage system according to claim18, wherein at least a first intermediate protective member is arrangedbetween the first wind turbine blade and the second wind turbine blade.21. The transportation and storage system according to claim 20, whereinthe first intermediate protective member is arranged near the tip end ofan upper arranged blade of the first wind turbine blade and the secondwind turbine blade.
 22. The transportation and storage system accordingto claim 20, wherein the intermediate protective member is made of afoamed polymer.
 23. The transportation and storage system according toclaim 14, wherein the first tip end frame comprises a first upwardlyfacing receptacle for supporting a part of the first wind turbine blade,and the second tip end frame comprises a second upwardly facingreceptacle for supporting a part of the second wind turbine blade. 24.The transportation and storage system according to claim 17, wherein thefirst longitudinal extent and the second longitudinal extent are atleast 3.5 metres.
 25. The transportation and storage system according toclaim 24, wherein the first longitudinal extent and the secondlongitudinal extent are at least 5 metres.